DDM 20210107

public String saveBitmapToImageFile(
            Bitmap pBitmap,
            String pFilename
    ){
        try{
            FileOutputStream fos = new FileOutputStream(
                    pFilename
            );

            if (fos!=null){
                /*
                Write a compressed version of the bitmap to the specified outputstream.
                If this returns true,
                the bitmap can be reconstructed by passing a corresponding inputstream to BitmapFactory.decodeStream().
                Note: not all Formats support all bitmap configs directly,
                so it is possible that the returned bitmap from BitmapFactory could be in a different bitdepth,
                and/or may have lost per-pixel alpha (e.g. JPEG only supports opaque pixels).
                 */
                Boolean bAbleToRepresentBitmapAsRequested = pBitmap.compress(
                        Bitmap.CompressFormat.PNG,
                        100,
                        fos
                );
                if (bAbleToRepresentBitmapAsRequested){
                    return pFilename;
                }
            }//if
        }//try
        //if an Exception does occur it is probably "FileNotFoundException"
        catch (Exception e){
            //probably: java.io.FileNotFoundException: test.png (Read-only file system)
            Log.e("BOINK!", e.toString());
        }//catch
        return ""; //could not save file
    }//saveBitmapToImageFile

//---

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageView
        app:layout_constraintTop_toTopOf="parent"
        android:id="@+id/idIvCapturedImage"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

    <!-- Text captured: -->
    <TextView
        android:gravity="center_horizontal"
        android:text="@string/strTvAbout"
        android:id="@+id/idTvAbout"
        app:layout_constraintTop_toBottomOf="@id/idIvCapturedImage"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"></TextView>

    <!-- the exact text that was shared from an external app will
    show here -->
    <TextView
        android:id="@+id/idTvCapturedText"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toBottomOf="@id/idTvAbout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <ListView
        android:id="@+id/idLvRecords"
        app:layout_constraintTop_toBottomOf="@id/idTvCapturedText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"></ListView>

</androidx.constraintlayout.widget.ConstraintLayout>

//

package com.joythis.android.textcapturer;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Map;

public class MainActivity extends AppCompatActivity {
    Context mContext;
    TextView mTvAbout, mTvCapturedText;
    ImageView mIvCapturedImage;

    ArrayList<String> mAlRecords;
    ArrayAdapter<String> mAd;
    ListView mLvRecords;

    public final static String MY_TSV_DB = "SHARES.DB";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        init();
    }//onCreate

    boolean qualityControl(
        Object[] pCheckThese
    ){
        boolean bRet = true;
        for (Object o : pCheckThese){
            bRet = bRet && (o!=null);
        }//for

        return bRet;
    }//qualityControl

    Map<Object, Boolean> altQualityControl(
        Object[] pCheckThese
    ){
        Map<Object, Boolean> aRet= new HashMap<>();
        for (Object o : pCheckThese){
            boolean bOk = o!=null;
            aRet.put(o, bOk);
        }//for
        return aRet;
    }//altQualityControl

    void init(){
        mContext = this;
        mTvAbout = findViewById(R.id.idTvAbout);
        mTvCapturedText = findViewById(R.id.idTvCapturedText);
        mIvCapturedImage = findViewById(R.id.idIvCapturedImage);

        mLvRecords = findViewById(R.id.idLvRecords);
        mAlRecords = new ArrayList<>();
        mAd = new ArrayAdapter<>(
            mContext,
            android.R.layout.simple_list_item_1,
            mAlRecords //memory address for the data
        );
        mLvRecords.setAdapter(mAd);

        Object[] aRelevant = {mTvAbout, mTvCapturedText};
        boolean bCanProceed = qualityControl(aRelevant);

        if (!bCanProceed){
            Toast t = Toast.makeText(
                this,
                getString(R.string.strThereIsNullObject),
                Toast.LENGTH_LONG
            );
            return;
        }//if

        mTvAbout.setText(
            whereIsThePrivateInternalStorage()
                +"\nText Captured:"
        );

        /*
        TODO: avoid reprocessing the Intent on reexecutions of onCreate
         */
        checkIfCalledForSharingAndDisplayingSharedData();

        refresh();
    }//init

    void checkIfCalledForSharingAndDisplayingSharedData(){
        Intent intentHowWasICalled = getIntent();

        if (intentHowWasICalled!=null){
            String strAction =
                intentHowWasICalled.getAction();

            //share
            boolean bIWantToAnswer =
            strAction.equals(Intent.ACTION_SEND);

            boolean bIWantToAnswer2 =
            strAction.compareTo(Intent.ACTION_SEND)==0;

            boolean bIWantToAnswer3 =
            strAction.compareToIgnoreCase(Intent.ACTION_SEND)==0;

            if (bIWantToAnswer){
                //it was a share!

                String strType =
                    intentHowWasICalled.getType();

                Toast.makeText(
                    mContext,
                    strType,
                    Toast.LENGTH_LONG
                ).show(); //"image/png" "image/jpeg"

                boolean bIsText =
                    strType.startsWith("text/");

                boolean bIsImage =
                    strType.startsWith("image/");

                if (bIsText){
                    String strTextThatWasShared =
                    intentHowWasICalled.getStringExtra(
                        Intent.EXTRA_TEXT
                    );

                    insert(strTextThatWasShared); //record the received text
                    refresh(); //shows the text

                    mTvCapturedText.setVisibility(View.GONE); //hides the TextView

                    //enough for principle demonstration
                    mTvCapturedText.setText(
                        strTextThatWasShared
                    );
                }//if text was shared
                else
                if (bIsImage){
                    //TODO?
                }
            }//if the Activity was called from an ACTION_SEND Intent (e.g. Share from another app)
        }//if got an Intent object with all the necessary data
    }//checkIfCalledForSharingAndDisplaySharedText

    void refresh(){
        /*
        String strNewContent = readFile(MY_TSV_DB);
        mTvCapturedText.setText(strNewContent);
         */
        //mAlRecords = new ArrayList<>(); //NO GO! would break the Adapter
        mAlRecords.clear();

        //mAlRecords.addAll(readFile(MY_TSV_DB)); //original order
        ArrayList<String> alTemp = readFile(MY_TSV_DB);
        for (int idx=0; idx<alTemp.size(); idx++){
            String strContent = alTemp.get(idx);
            mAlRecords.add(0, strContent);
        }//for

        mAd.notifyDataSetChanged();
    }//refresh

    /*String*/ArrayList<String> readFile(
        String pFileName
    ){
        String strContent =
        readFromPrivateInternalStorage(pFileName);

        /*
        somewhat useless while the app is not rewritten using
        a true "Record" class data type
        and a collection of Records is kept (for example in ArrayList<Record>)
         */
        ArrayList<String> aRet = new ArrayList<>();
        String[] aRecords =
            strContent.split("\n");
        for(String record : aRecords){
            String strAfterReplacement =
            record.replace(
                "<br>", "\n"
            );
            aRet.add(strAfterReplacement);
        }//for
        return aRet;

        //return strContent;
    }//readFile

    /*
    will record with a TSV structure of our imagination
    the data in a file, in the private internal storage of the app

    <when> \t <text> \n
     */
    void insert(String pStrWhatToInsert){
        Calendar cal = Calendar.getInstance();
        String strYMD = String.format(
            "%d-%d-%d",
            cal.get(Calendar.YEAR),
            (cal.get(Calendar.MONTH)+1),
            cal.get(Calendar.DAY_OF_MONTH)
        );

        //replace the TSV reserved-symbols for innocuos alternatives
        // \n -> "<br>" ; \t -> " "
        String strAfterReplacement =
            pStrWhatToInsert.replace(
                "\n",
            "<br>"
            );

        strAfterReplacement =
            pStrWhatToInsert.replace(
                "\t",
                " "
            );

        String strRecord = String.format(
            "%s\t%s\n",
            strYMD,
            strAfterReplacement
        );

        Boolean bOK =
            writeToPrivateInternalStorage(
                MY_TSV_DB,
                //pStrWhatToInsert+"\n",
                strRecord,
                MODE_APPEND
            );

        if (bOK){
            Toast t = Toast.makeText(
                mContext,
                "New record added to TSV DB",
                Toast.LENGTH_LONG
            );
            t.show();
        }//if
    }//insert

    /*
    to read and write in the Private Internal Storage
    we need tools for dumping and recovering text from
    that exclusive non-volatile file-system area
     */

    String whereIsThePrivateInternalStorage(){
        File pis = this.getFilesDir();
        return pis.getAbsolutePath();
    }//whereIsThePrivateInternalStorage

    Boolean writeToPrivateInternalStorage(
        String pFileName,
        String pFileContent,
        int pWriteMode //PRIVATE (destructive) / APPEND (cumulative)
    ){
        try {
            FileOutputStream fos = openFileOutput(
                pFileName,
                //MODE_APPEND
                pWriteMode
            );

            if (fos!=null){
                OutputStreamWriter osw = new OutputStreamWriter(
                    fos,
                    StandardCharsets.UTF_8
                );
                if (osw!=null){
                    osw.write(pFileContent);
                    osw.close();
                    fos.close();
                    return true;
                }//if
            }//if
        }//try
        catch (Exception e){
            Log.e(
                getClass().getName(),
                e.toString()
            );
        }//catch
        return false;
    }//writeToPrivateInternalStorage

    String readFromPrivateInternalStorage(
        String pFileName
    ){
        try{
            FileInputStream fis = this.openFileInput(pFileName);
            if (fis!=null){
                InputStreamReader isr = new InputStreamReader(
                    fis,
                    StandardCharsets.UTF_8
                );

                if (isr!=null){
                    int i; char c; String strAll="";
                    while ((i=isr.read())!=-1){
                        c = (char) i;
                        strAll+=c;
                    }//while
                    isr.close();
                    fis.close();

                    return strAll;
                }//if
            }//if
        }//try
        catch(Exception e){
            Log.e(
                getClass().getName(),
                e.toString()
            );
        }//catch

        return "";
    }//readFromPrivateInternalStorage
}//MainActivity